128 BIRDS OF THE PLAINS 



laid in open nests are protectively coloured would do 

 well to ponder. 



There, side by side, in precisely the same environment, 

 were two nests one containing white and the other dark 

 blue eggs. Obviously both sets of eggs could not be 

 protectively coloured ; as a matter of fact, both clutches 

 of eggs were conspicuous objects. It not infrequently 

 happens that the Indian robin ( Thamnobia cambayensis), 

 which lays white eggs thickly spotted with reddish 

 brown, brings up a family in a disused nest of a striated 

 bush babbler's. The eggs of this latter are dark blue. 

 It is surely time that zoologists gave up throwing at us 

 their everlasting theory of protective colouring. If this 

 were a sine qua non of the safety of birds' eggs, then the 

 whole dove tribe would, long ago, have ceased to exist. 



This family presents the ornithologist with yet 

 another problem in colouration. In every species, 

 except the red turtle-dove (Oenopopelia tranquebaricd], 

 both sexes are coloured alike. In this latter, however, 

 there is very pronounced sexual dimorphism. The 

 ruddy wing feathers of the cock enable one to dis- 

 tinguish him at once from his mate and from every 

 other dove. Now the habits of this dove appear to be 

 exactly like those of all other species. It constructs 

 the same kind of nest and in similar situations ; why 

 then the sexual dimorphism in this species and in no 

 other species ? If the lady rufous turtle-dove likes nice 

 ruddy wings, and thus the red wing has been evolved in 

 the cock bird, why has she too not inherited it? I 

 presume that even the most audacious Neo-Darwinian 

 will not talk about her greater need of protection when 



